You've got a problem ... unless the fermentation is taking place and you don't know it. I think it would be almost impossible to not know that fermentation has occurred, but that depends on your setup.

For instance, if you weren't around for the first 24 hours or so, it's possible that high krauesen did occur, and that the fermentation has merely slowed down since then. However, if you had any respectable krauesen, there would be signs on the sides of the bucket or the top of the carboy. If they are clean, then it is fairly apparent that you did not have high krauesen, in which case, I doubt that you can salvage the beer after four days because I'd bet my last dollar that it has soured.

Now, if there are signs that krauesen has occurred, then the question becomes: how do you know that it is not still slowly fermenting. If you are using an airlock, it _could_ be possible that it is not seated well enough to seal the fermenter and therefore CO2 is escaping around the stopper/lid. But that seems highly unlikely with a carboy, but I could envision it happening with a bucket with a lid that isn't tightly sealed.

At this point I would recommend that you sanitize something to take a sample; I have a 'thief', but since you haven't posted very long, I assume that you are just beginning and might not have one. You can sanitize a siphon starter, or a 'baster' (the thing with a squeeze bulb used to baste turkeys, etc.), or you can use a length of sanitized plastic tube, or even a sanitized straw -- so long as it is sanitized "just in case" you can salvage this. The first thing is to smell and taste the sample; hydrometer and refractometer readings won't matter if this is infected/souring. If it doesn't seem infected, then take a gravity reading and compare it with your O.G. (you _should_ have taken one). If the gravity is dropping, then it is fermenting ... by yeast or bacteria, one or the other.

If it's fermenting, then give it time to finish, etc.

If it's NOT fermenting and is soured or medicinal, toss it ... unless you like sour beer and/or lambics or whatever.

If it's NOT fermenting and tastes okay ... which would amaze me ... then aerate it again in a sanitary way, and then re-pitch your yeast.

Finally, if it hasn't fermented, you need to learn why and correct your procedures. Even very old yeast packs will usually eventually start fermentation, so I suspect that the more likely cause is that you tried to pitch while your wort was too hot (which would probably really need to be above 100F to actually kill the critters), or you had residual sanitizer in your fermenter that killed the yeast. Unless your yeast was VERY old and NOT stored well at all, I'd guess that you probably over did it on the sanitizer ... because surely you could tell if your wort was over 100F.

If you mean there's no bubbles in the airlock and you're using a bucket, the lids are infamous for not being airtight. So, you might have fermentation and not see bubbles in the airlock. If so, open the lid and look for signs like those described by Bill.

Cappy...glad your Red is turning out! I know that "WHEW" feeling when you find out your yeast is working.

I too use a plastic bucket-type primary, and I've found that the lid tends to leak, causing no bubbling in the blow-off tube or air lock. As a result, I use whatever heavy items in my pantry (also known as my primary fermentation station) to weigh the lid down to create a better seal...usually boxes of canned tomatoes or large juice bottles placed around the edge of the lid and leaning on the walls of the pantry.

I know it's not perfect, but it works. This seems to limit the risk of infection (none yet, knock on wood) and I can see/hear that wonderful yeast doing it's thing without having to worry.

Not sure which brand of lids you have available to you but I have had great luck w/ Ropak brand lids.I got 1 from my LHBS-The home brewery and the other from midwest supplies. Both will seal on any of 3 different buckets I have. Several being cheap 5gals. from the mega-mart.The 1st. time I used them I had to put all my weight on them to pop them over the buckets,I thought I was gonna break them.